Vaadin server-side elements for other polymer elements

I am trying to use additional polymer elements than the one’s in the server side elements demo, for e.g. paper-card.

I assumed that I can just add the relevant files in bower-components folder and create a demo class like paper-button.

However, it doesn’t seem to work. So does the server-side elements only work for polymer paper-slide and paper-button?

It should work with other elements as well. Would you maybe like to share your code here?